PHOTOBIOLOGY OF LUPUS-ERYTHEMATOSUS

Background. Although cutaneous photosensitivity is one of the major cr iteria used for the diagnosis of systemic lupus erythematosus, this cr iterion is not precise. Objective. To evaluate the interest of photobi ological exploration in patients with cutaneous lupus erythematosus, a nd to compare the results to clinical photosensitivity. Methods. Ninet een patients consecutively seen in one year, have been tested using a standardized method. Results. Clinical photosensitivity was present in 16 cases. The clinical presentation of cutaneous disease was classifi ed in 3 groups: acute, subacute, and chronic. One patient with no hist ory of photosensitivity had positive photobiological tests, and five p atients had negative tests though they experienced clinical photosensi tivity. Positive phototests with UVA and WE were present in 6/8 subacu te lupus cases, 3/6 acute lupus cases, 3/5 chronic lupus cases. Histol ogical aspect of cutaneous biopsies from phototest was not characteris tic of lupus. Minimal erythematous doses was comparable in lupus group and in controls. No correlation between positivity of phototests and the presence of systemic involvement or anti-Ro/SSA antibodies was est ablished. Conclusion. Phototesting is useful to assess photosensitivit y in lupus patients.